热挤压AZ81镁合金的拉伸变形行为

Tensile deformation behavior of hot-extruded AZ81 magnesium alloy

为了确定试验温度和应变速率对热挤压AZ81镁合金拉伸变形行为的影响规律，在不同温度和应变速率下对其进行了拉伸试验，结合透射电镜分析了热挤压AZ81镁合金的微观组织结构与其拉伸变形行为间的关系．结果表明：在一定的应变速率和试验温度范围进行拉伸变形时，热挤压AZ81镁合金可发生动态应变时效，其中当应变速率在5×100^-5-1×10^-4s^-1范围时，动态应变时效发生的温度范围为125～200℃，而当应变速率为5×10^-4s^-2时，动态应变时效发生的温度范围为150~200℃．在相同应变速率下，随着试验温度的升高，合金中的位错密度增大，位错与溶质原子的交互作用增强．

In order to clarify the influence of both testing temperature and strain rate on tensile deformation behavior of the hot-extruded AZ81 magnesium alloy, the displacement-controlled tensile experiments were performed at different temperatures and strain rates. In addition, the relationship between the microstructures and tensile deformation behavior of the extruded AZ81 alloy was studied based on the transmission electron microscope analysis. The experimental results show that the so-called dynamic strain aging can be observed during the tensile deformation of the extruded AZ81 alloy in some certain range of temperatures and strain rates. The dynamic strain aging occurs in the temperature range of 125--200 ℃ at the strain rates ranging from 5 × 10^-5 s^-1 to 1 × 10^-4 s^-1 while it appears in the temperature range of 150-200 ℃ at the strain rate of 5 × 10^-4 s^-1. With test temperature increasing, the dislocation density inside the deformed AZ81 alloy increases, and the interaction between mobile dislocations and solute atoms gets enhanced.